Purification and characterization of a D-mannose specific lectin from the green marine alga, Bryopsis plumosa

P>A d-mannose specific lectin was purified from the green marine alga, Bryopsis plumosa (Huds.) Ag. The lectin agglutinated horse and sheep erythrocytes. Matrix assisted laser desorption/ionization time of flight mass spectrometry, size exclusion chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two dimensional gel electrophoresis (2DE) results showed that the lectin was a monomer with molecular weight of 17 kDa and pI 7.3. The agglutinating activity was inhibited by d-mannose (1 mM), alpha-methyl-D-mannose (4 mM) and l-fucose (8 mM). d-glucose (125 mM) showed weak inhibition. The lectin did not need divalent cations for agglutinating activity. N-terminal amino acid sequence of the lectin was analyzed. As the lectin was novel, we named it BPL-2 (Bryopsis plumosa lectin 2). Full cDNA sequence of BPL-2 was obtained using cDNA library. It was comprised of 624 bp of open reading frame and 167 bp/57 bp of 3'/5' untranslated regions as well as N-terminal signal peptide. No antimicrobial activity of BPL-2 was observed in four bacteria strains tested.